The waterpumps suck in these. The plastic impellers crack and break and hardly push any coolant. Typically before 100k miles.
What's the build date on your 04?
3C3Z-8501-A is for PMP ASY-WTR - 2002.5 to 7/18/2004
4C3Z-8501-AC is for PMP ASY-WTR - 7/19/2004 and up
Early one's are a 90mm impeller later one's are 100mm.
OEM are $160 or so from Tousley Ford Parts Depot
Bulletproof diesel also makes one now with a billet aluminum impeller blades... they're like $220
[ ] Bullet Proof Diesel Water Pump, Ford 6.0L Diesel